An internal combustion engine may include a plurality of cylinders, each cylinder of the plurality of cylinders may including a piston disposed there. Each cylinder of the plurality of cylinders may be capped by a cylinder head to form a plurality of combustion chambers. In one embodiment, the internal combustion engine may be configured to receive fuel via direct injection. In other words, the plurality of combustion chambers may receive fuel (e.g., gasoline) via a plurality of fuel injectors, with each fuel injector of the plurality of fuel injectors disposed within a separate combustion chamber. One or more intake ports with separate intake valves disposed within each intake port may be coupled to each combustion chamber in order to supply a combustible gas (e.g., air) to each combustion chamber. The injected fuel and air may mix and be combusted within each combustion chamber. The resulting gases from combustion may then exit each combustion chamber via one or more exhaust ports coupled to each combustion chamber, with separate exhaust valves disposed within each exhaust port.
Vehicles including an internal combustion engine configured for direct injection as described above often experience hydrocarbon emissions as a result of uncombusted fuel exiting the combustion chambers via the exhaust ports. Uncombusted fuel may include fuel that accumulates on surfaces of each combustion chamber and/or piston due to fuel injector arrangement, spark plug arrangement, improper air/fuel ratio, etc.
Attempts to address reducing hydrocarbon emissions from an engine include configuring each piston and combustion chamber to decrease an amount of fuel accumulation on surfaces of the combustion chamber and/or piston. One example approach is shown by Kanda et al. in U.S. Pat. No. 6,257,199. Therein, a direct fuel injection-type spark ignition internal combustion engine is disclosed including a cavity formed in a top surface of a piston. Fuel is sprayed by a fuel injector into the cavity, and the fuel is then directed towards a spark plug by a plurality of walls formed by the cavity. Another example approach is shown by Akimoto et al. in U.S. Pat. No. 5,960,767. Therein, a combustion chamber of an in-cylinder direct fuel injection spark ignition engine is disclosed, with a top surface of the combustion chamber including an intake side surface and an exhaust side surface. The combustion chamber additionally includes a piston with a cavity formed within a top surface of the piston in order to reflect a fuel spray injected into the combustion chamber via a fuel injector.
However, the inventors herein have recognized potential issues with such systems. As one example, fuel injected towards a cavity of a piston may increase an amount of fuel in contact with surfaces of the piston. This may result in an increase in fuel accumulation on surfaces of the piston, which may increase an amount of hydrocarbon emissions from an engine due an incomplete combustion of the fuel. As another example, fuel injected into a combustion chamber during an end of a compression stroke of an engine (e.g., when a piston translates towards a top surface of the combustion chamber) may have an increased likelihood of accumulating on surfaces of the combustion chamber and/or piston due to a decreased volume of the combustion chamber during the compression stroke. In other words, when the piston approaches its highest position (e.g., a position nearest a cylinder head of the engine), the volume of the combustion chamber is decreased and a fuel injection distance may be decreased. This may result in incomplete combustion due to a decreased mixing of fuel and intake air.
In one example, the issues described above may be addressed by a system comprising: a cylinder head including a first cylinder surface coupled to an intake port and a second cylinder surface coupled to an exhaust port, the second surface angled relative to the first surface; and a piston including a first piston surface arranged parallel to and vertically in-line with the first cylinder surface and a second piston surface arranged parallel to and vertically in-line with the second cylinder surface. As one example, the cylinder head may include a third cylinder surface parallel to and above the first cylinder surface, and the third cylinder surface may be coupled with a fuel injector. The fuel injector may be arranged to inject fuel at an angle relative to the third cylinder surface and towards a first side of the combustion chamber. The fuel injector may additionally be configured to inject fuel during a start of a compression stroke or an end of an intake stroke of an engine. By configuring the cylinder head and piston in this way, a path of fuel injected into the combustion chamber may be increased. The longer fuel path may increase an amount of mixing of the fuel with intake air, which may reduce an amount of fuel deposited on surfaces of the combustion chamber and may increase an amount of fuel combustion within the combustion chamber. In this way, hydrocarbon emissions may be reduced and a fuel efficiency of the engine may be increased.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
FIGS. 2-5 are shown to scale, though other relative dimensions may be used.